sympy/utilities/pkgdata.py

   1 """
   2 pkgdata is a simple, extensible way for a package to acquire data file
   3 resources.
   4
   5 The getResource function is equivalent to the standard idioms, such as
   6 the following minimal implementation::
   7
   8     import sys, os
   9
  10     def getResource(identifier, pkgname=__name__):
  11         pkgpath = os.path.dirname(sys.modules[pkgname].__file__)
  12         path = os.path.join(pkgpath, identifier)
  13         return file(os.path.normpath(path), mode='rb')
  14
  15 When a __loader__ is present on the module given by __name__, it will defer
  16 getResource to its get_data implementation and return it as a file-like
  17 object (such as StringIO).
  18 """
  19
  20 import sys
  21 import os
  22 from cStringIO import StringIO
  23
  24 def get_resource(identifier, pkgname=__name__):
  25     """
  26     Acquire a readable object for a given package name and identifier.
  27     An IOError will be raised if the resource can not be found.
  28
  29     For example::
  30         mydata = get_esource('mypkgdata.jpg').read()
  31
  32     Note that the package name must be fully qualified, if given, such
  33     that it would be found in sys.modules.
  34
  35     In some cases, getResource will return a real file object.  In that
  36     case, it may be useful to use its name attribute to get the path
  37     rather than use it as a file-like object.  For example, you may
  38     be handing data off to a C API.
  39     """
  40
  41     mod = sys.modules[pkgname]
  42     fn = getattr(mod, '__file__', None)
  43     if fn is None:
  44         raise IOError("%r has no __file__!")
  45     path = os.path.join(os.path.dirname(fn), identifier)
  46     loader = getattr(mod, '__loader__', None)
  47     if loader is not None:
  48         try:
  49             data = loader.get_data(path)
  50         except IOError:
  51             pass
  52         else:
  53             return StringIO(data)
  54     return file(os.path.normpath(path), 'rb')
  55